Boku no Seiso na Mama ga, Konna ni Inran na Wake ga Nai! ~Bitch Mama to no Futekisetsu na Kankei~

Synopsis

I was caught in a sudden rain and ran into an underground passage. I decided to take shelter for a bit to see what was going on, and just as things started to calm down... I heard something from the back of the passage. Perhaps a moan? I heard an unusual woman's voice coming from the depths of the underground passage. (Could it be... in a place like this?) No matter how deserted the area was, it was still incredibly bold to do something lewd in the middle of the day. (Are they really... doing something naughty...?) I sneaked my footsteps down the stairs. Holding my breath, I peered into the depths of the passage. (Wow... they were really doing it.) A woman was straddling the man, who was lying on his back, shaking her hips. The woman was bouncing her buttocks vigorously. They were both fully clothed, so their physical union was invisible, but they were undoubtedly engaged in sexual intercourse. Even though it was an underground passage with little foot traffic, having sex in a public place where they might be seen... "Oh, no... I've had enough." The man was finally giving in to the woman's lewd hip movements. "Not yet, just a little more... You're young, hold on a little longer..." Hearing the woman's voice scolding the man... a thought suddenly occurred to me. (Huh... I feel like I've heard this voice somewhere before...) I was taken aback. It wasn't just "I've heard it somewhere before." I hear it every day. (Mom...) "Oh... Ah... Ahh... Ah... Good... A young, energetic 'man'... So good." Unable to bear it any longer, I ran away.